6 Best electrical shims for recessed outlet leveling

Recessed outlets are a common headache during finish work, often hidden behind new backsplashes, thick drywall, or layered flooring. When a box sits too deep, a standard faceplate will hover against the wall rather than seating flush. Solving this requires more than just longer screws; it demands reliable shimming or extending to ensure a fire-safe, code-compliant connection. The following guide breaks down the best solutions for bringing those outlets back to the surface.

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Ideal Industries Spacers: The Pro’s Go-To Shim

Ideal Industries spacers function like a series of tiny, compressible gaskets that slide over the outlet mounting screws. They are favored in fast-paced commercial environments where precision adjustments are needed without pulling the device wires.

The primary benefit is the ability to snap segments off to reach the exact depth required. If the wall finish is slightly uneven, a single stack of these spacers can bridge the gap perfectly.

• Pro Tip: Always ensure the device mounting strap is fully supported against the box or the wall surface. Using these on a loose box does not compensate for structural movement behind the drywall.

Arlington BE1: Best Extender for Tile & Stone

When dealing with stone veneer or thick tile, standard spacers simply aren’t enough. The Arlington BE1 serves as a rigid, box-extender that provides a solid surface for the outlet to mount against.

This is the preferred choice when the electrical box is buried deep within a masonry or tile substrate. Because it creates a non-conductive, rigid ring, it provides a much more stable foundation than stacked plastic spacers.

• Bottom Line: For high-traffic areas or heavy-duty use, the rigid support of the BE1 outperforms compressible shims. It keeps the outlet from “sinking” every time a plug is pulled from the socket.

ReceptXtenders: Easiest Install for DIY Projects

ReceptXtenders are designed with simplicity in mind, often featuring a friction-fit or simple screw-through design. They act as a physical bridge between the old box and the new wall surface.

These units are ideal for minor renovations where the outlet box is only recessed by an eighth or a quarter of an inch. They provide a clean, finished look that eliminates the gap between the plate and the wall.

• Reality Check: While these are excellent for DIYers, check the total depth before installation. If the box is recessed more than 3/4 of an inch, a standard extender might leave the wires too tight or unsupported.

Gardner Bender Spacers: Top Bulk Value for Big Jobs

Gardner Bender offers multi-packs of spacers that are essentially a commodity in the electrical trade. These are the “go-to” when the job site has dozens of outlets to calibrate after a whole-home renovation.

They work by filling the void between the mounting strap and the box ears. Because they are inexpensive and come in bulk, there is never a concern about running out of material mid-project.

• Strategic Use: Keep a container of these in the truck. They are the ultimate “problem solver” for that one outlet that sits just deep enough to be annoying, but not deep enough to warrant a full box extender.

RACO 907C: Best Metal Extender for Code Compliance

In commercial settings or local jurisdictions with strict fire-safety requirements, plastic extenders may be prohibited. The RACO 907C is a steel box extender designed to maintain the integrity of the electrical enclosure.

Metal extenders ensure that if a short-circuit occurs, the spark is contained within a grounded metal box. They are non-combustible and provide the highest level of protection in residential and commercial retrofits.

• Pro Consideration: Installing a metal extender requires a bit more finesse to ensure the grounding path remains continuous. Always check local code, as many inspectors demand metal-on-metal protection for commercial walls.

Stackable Spacers: Best for Precision Leveling

Stackable spacers are the modular Swiss-Army knife of electrical leveling. They allow for incremental depth adjustments that standard washers or rigid extenders cannot provide.

They are particularly useful when the wall surface is slightly out of plumb. By stacking a different number of spacers on the left and right mounting screws, an outlet that would otherwise sit crooked can be brought perfectly flush and level.

• Decision Framework: If you are dealing with a “wavy” wall surface, ditch the single-piece extenders. Use individual stackable spacers to shim the device until the faceplate sits perfectly flat against the wall plane.

Shim vs. Box Extender: Which Do You Really Need?

The choice between a shim and an extender comes down to the depth of the recess. A shim is intended to push the device strap forward just enough to contact the back of the cover plate.

A box extender, conversely, is meant to extend the physical walls of the electrical box toward the finished surface. If the box is recessed by more than 1/4 inch, building codes generally dictate that an extender must be used to ensure the wiring is properly enclosed.

• Bottom Line: Use shims for minor adjustments (less than 1/4 inch) where the outlet strap still has solid contact with the box. Use an extender for deep recesses to ensure the wiring remains safely contained within the wall cavity.

Choosing the Right Screw Length for Your Spacers

One of the most common mistakes is failing to account for the added depth of the spacers. Standard 6-32 outlet screws will often come up short once you add 1/2 inch of shimming.

Always keep a stash of 1-1/2 inch and 2-inch 6-32 machine screws on hand. Never be tempted to use wood screws or drywall screws to secure an outlet; the threads and gauge are not designed for the mounting holes on an electrical device.

• Pro Tip: If the screw is too long, use a side-cutting plier (linesman pliers) to trim it to the correct length. It is better to have a screw that is slightly long and cut it than to find yourself short-handed mid-installation.

Electrical Code and Safety for Outlet Spacing

Electrical code, specifically the National Electrical Code (NEC), requires that electrical boxes be mounted flush with the finished wall surface, or within 1/4 inch for non-combustible surfaces. If the gap is larger, the box must be extended to meet the face of the wall.

This is not just about aesthetics; it is about preventing fire hazards. An outlet that is not properly supported is prone to loose connections, which can lead to arcing and overheating inside the wall.

• Safety Priority: If you cannot get a rigid, secure fit, the box is not properly installed. Never rely on the faceplate screws to pull the outlet into place; the device itself must be secured firmly to the box or the extender.

How to Install Outlet Shims: A Step-by-Step Guide

First, kill the power at the main panel to ensure you aren’t working on a live circuit. Remove the wall plate and unscrew the outlet from the electrical box.

Pull the outlet out gently—do not disconnect the wires if you have enough slack. Choose the appropriate number of shims or the right extender size to match your wall depth.

Place the shims over the mounting screws between the device strap and the box ears. Test the fitment by tightening the screws to ensure the outlet sits flush with the wall. If the outlet feels loose or unstable, move to a rigid box extender instead of using a stack of shims.

• Final Verification: Once the outlet is set, replace the cover plate and check that it sits flat against the wall without any gaps. Turn the power back on and verify the outlet is functional and secure.

Getting your electrical outlets perfectly flush is the mark of a craftsman who respects the finished product. While the hardware itself is inexpensive, taking the time to select the right spacer or extender ensures a durable, code-compliant finish that prevents future headaches for the homeowner.